A randomised, triple blind, cross-over design human intervention studies will be conducted in 10 healthy human volunteers to test the impact of alkalisation on the absorption, metabolism and vascular reactivity of cocoa flavanols. Participants will be requested to consume a standardised high flavanol-rich cocoa, non-alkalised (1745 mg of flavanols), a low-flavanol cocoa, heavily alkalised (1.3 mg of flavanols) and a flavanol-rich cocoa, medium alkalisation (410 mg of flavanols). The three intervention diets are otherwise matched for macro- and micronutrient content. Vascular measurements will be performed by using Flow Mediated Dilation (FMD), Laser Doppler imaging (LDI) and Digital Volume Pulse (DVP). Blood and urine samples will be taken to measure the concentration of flavonoids from the cocoa drinks and markers of blood vessel function. A number of other biochemical and physiological measures will be recorded including blood glucose, lipoproteins, cytokine levels and blood pressure.